So, I got a surprise when I woke up the other day and saw that George C Marshall High School had turned into an average school overnight (the GreatSchools rating dropped from a stellar 9 to an average 7.) At first I wasn’t sure what had happened – did they fire a bunch of teachers (and thereby changed the student to teacher ratio?) Did the construction result in all the great students leaving? Did they cancel their IB program? Did the Marshall Statesmen loose all their games?
Nope. It would seem that all that happened was that the 2012-2013 standardized test scores were loaded into GreatSchools.org and that all the ratings were recalculated. This resulted in some schools previously rated 10 and 9 dropping 2 or 3 points (George C Marshall being one of those.) A few schools increased their scores as well.
Here are the old and new scores for some schools (read the rest at http://soldsense.com/2014/02/20/school-ratings-come-and-school-ratings-go)